1. Field of the Invention
This invention relates to a sterilization method that uses liquid disinfectant for sterilizing a filler pipe and piping in fluid communication therewith, in a sterile liquid-content packing machine.
2. Description of Background Art
In the manufacture of single-life package containers sterile-packed with liquid products such as milk or juice, web material used for packaging the contents is bent as it passes through a packing machine after sterilization. The lengthwise edges of the material slightly overlap mutually as a seal thus forming a tube, whereby the contents are supplied continuously from a filler pipe extending inward from the upper open end of the tube. As the tube travels lower, the tube is sealed as its prescribed position is pushed flat, whereby the contents level is automatically controlled so that it is sufficiently above the position where the seal is provided. Once sealed the tube separates horizontally at the sealed position, and the manufacturing process is completed after the prescribed reforming.
For a packing machine of the type described above, filling proceeds under sterilized conditions for sterile-packing manufacture. Thus, before executing filling operations at the packing machine, sterilization of the filler pipe, the piping for the product, a sterile-air inlet pipe and piping connected to the inlet to feed air so that unsterile air does not intrude from the outside of the filler pipe into contact with the upper portion of the contents in the web tube. Conventional machines sterilized the above members by use of high-temperature heated air. Recent machines sterilize with vaporized steam of hydrogen peroxide at a lower temperature to avoid the ill effects of the heat on the valve packings along the piping and web. Sterilization with hydrogen peroxide involves the spraying of liquid hydrogen peroxide, an aqueous solution of hydrogen peroxide, by opening a nozzle at a mixing chamber established along the piping that feeds heated air, and requires the production of steam. A mixture of the steam and heated air is fed to filler piping, piping, and other parts requiring sterilization. For example, in order to disinfect filler pipes and piping requiring sterilization, the method described in Japanese Patent Publication No. 53-47548, wherein the embodiment discloses the disinfecting of a web, involves disinfectant spray-mixed and vaporized with a high-temperature air stream where the mixed-air dew point has a higher temperature than the surfaces to be disinfected, so that the disinfectant cools and evenly condenses in layers over the surfaces to be disinfected. Subsequently, the disinfectant is removed. In application, the surface temperatures of parts requiring sterilization are cooled initially from the high temperatures generated from preheating operations of the packing machine, etc., followed by sterilization with a mixture of hydrogen peroxide steam and heated air.